Pet food product and method of producing same

ABSTRACT

A pet food product is produced having a coloured exterior that simulates the appearance of real meat that has been a marinated or grilled appearance. The product may be manufactured using a vegetarian (meat free) formulation or a formulation combining meat with dry proteinaceous materials. The ingredients are processed to form an emulsion-like mixture, which is rapidly heated in a confined zone to allow the protein to coagulate. An injector/shredder assembly is positioned in the zone to disrupt and shred the coagulated product mass and inject a colourant. The colourant adheres to some of the exterior surfaces of the final product to create a simulated grilled or roasted appearance.

BACKGROUND OF THE INVENTION

This invention relates to the production of pet food products with arandom colouring on the surface having a meat-like and, but not limitedto, a roasted or marinated appearance and texture. Colourants are addedto the exterior of the individual pieces of the product of the presentinvention to enhance the appearance of the food product.

Simulated meat products are well known in the pet food industry. Priorefforts directed to providing simulated natural meat chunks for pets aredisclosed in U.S. Pat. No. 4,781,939. In this '939 patent, a meatemulsion is pumped through an emulsion mill where it is subjected toshearing to increase the fineness of the emulsion and almostsimultaneously heat the emulsion to between about 104° C. toll 8° C. Thehot meat emulsion is then pumped by centrifugal force into a confinedprocessing zone, sometimes referred to by those in the industry as a“hold tube”. While passing through the elongated hold tube, proteincoagulation of the emulsion proceeds at a rapid rate. One or more pinchvalves could be positioned in the hold tube to control flow. A cuttingmeans was mounted at the discharge end of the elongated hold tube to cutthe coagulated product into pieces of a desired size, e.g. from about1.2 to 5 cm or more. The '939 patent describes the finished product asbeing formed into discrete pieces or chunks having a distinct layeredstructure which simulates pieces of natural meat in texture andappearance.

International Publication No. WO 01/35766 presents other efforts toproduce a meat emulsion product with a meat like appearance. FIG. 2 ofthis International Publication is a photograph of the meat emulsionproduct produced in accordance with the teachings of this prior artdisclosure. As can be seen in the photograph, the product has aplurality of elongate strands of fibers that are generally linearlyarranged in bundles. To some, the end product resembles pulled pork. ThePublication itself describes the appearance as tender slow cookedchicken or turkey that has been hand-pulled from the bone and covered inits own broth/juice. The product in this prior art disclosure isproduced in a hold tube that defines a confined processing zone. Priorto entering the hold tube the emulsion is pumped through an emulsionmill in which the emulsion is subjected to shearing to increase thefirmness of the emulsion and almost simultaneously heat the emulsion tobetween about 120° to about 163° C.

Other efforts have been made to improve the appearance of emulsionproducts, especially in the field of pet treats and pet foods. Forexample, Alpo® Prime Treats are soft treats shaped like little T-bonesteaks with a series of parallel dark marks on the top of the treat thatgive the appearance of grill marks such as those imparted from the hotbars or hot rungs of an outdoor barbecue grill or the grate of any othertype of grill. This appearance is imparted to the pet treat by a hotelement that actually sears a plurality of parallel dark marks into thesurface of the treat.

Despite these and other efforts, there is still a need for pet foodproducts with improved appearance. There is still a need for an easierand more economical way to impart a simulated grilled or marinatedappearance to pet food products.

SUMMARY OF THE INVENTION

Pet food products having the form of solid, meat-like chunks, areproduced using the production process of the present invention. Theproducts of the present invention have a base colour and randomcolouring on some exterior surfaces which simulates a roasted or grilledappearance that is desirable to consumers. The roasted or grilledappearance is achieved through the addition in situ of colourants tosome exterior surfaces of the product during the production process, notthrough the direct application of a heating element to the product.

Thus, according to a first aspect of the invention, a pet food productcomprises individual pieces of a food product mass having a base colorand a contrasting exterior color that simulates grill marks on naturalmeat that has been chopped into irregularly shaped individual piecesprior to serving.

In a preferred form of the invention, the said pieces consist of asolidified emulsion comprising at least one of a meat source, a dryproteinaceous source and a vegetarian food source.

In a further preferred form of the invention, the exterior colorcomprises a colorant selected from the group consisting of water-solublecolorants and oil-soluble colorants. The colorant preferably adheres tothe emulsion without the presence of a binder.

In a still further preferred form of the invention, the colorant isnegatively charged with respect to said product mass pieces to promoteadhesion of said colorant to said pieces.

Preferably, the pieces comprise less than 15% fat by weight.

Preferably, the pieces have a moisture content from about 50% to about65% by weight.

According to a second aspect of the invention, there is provided processfor producing a pet food comprising:

-   mixing a protein source to produce an emulsion;-   heating said emulsion above the boiling point of water;-   pressurizing said emulsion in a confined pressurized zone;-   coloring said emulsion in said confined pressurized zone; and-   discharging said emulsion in discrete pieces or chunks of pet food.

The protein source may comprise at least one of a vegetable source, ameat source, and a meat by-product source.

The vegetable source may comprise at least one of a soy source, a cornsource, a rice source, a peanut source, a sunflower source, a linseedsource, a canola source and a wheat source.

The meat source may comprise at least one of a beef source, a chickensource, a fish source, and a pork source. In an embodiment, the meatsource contains from about 15% to about 25% fat by weight. In analternative embodiment, the meat source contains less than 15% fat byweight.

In an embodiment, the process results in a product that simulatesmarinated or grilled beef that has been chopped into irregular chunks.Some portions of the exterior surface are darker than the underlyingbase colour of the product, giving a simulated grilled or marinatedappearance.

In an embodiment, the exterior coloration is added by means of aninjector/shredder assembly at the time of formation of the solid bodyduring the production process. The invention can also be used to produceproducts with some exterior surface colouration that simulate grilledfish or chicken. Furthermore, the invention can be used with vegetableprotein sources to simulate a variety of coloured meat products.

A serving of the product produced by this invention has a number ofindividual pieces with different shapes and sizes that closely simulatenatural meat that has been cooked and chopped prior to serving. The sizerange of the individual chunks is variable, but they typically includesmall, medium and larger chunks in each serving, with some individualpieces falling intermediate of these three general classes.

Furthermore, a majority of the individual pieces tend to have irregularsurface contours over at least a portion of the chunk. Some individualpieces may have one or more flat surface contours due to being resizedby cutting equipment, which causes the flat cut surface. The overallappearance of the end product produced by this invention is a variety ofindividual pieces of different shape, one from the other and most of theindividual pieces also having irregular exterior surface contours toclosely simulate natural meat products that have been chopped andgrilled or pan fried prior to serving. The colourant causes many of theindividual pieces to have a portion of the exterior surface darkened asthough seared, for example, on an outdoor barbecue grill or any grillwith a hot grate that imparts sear marks or dark marks to the piece byburning the surface. Nevertheless, the colouring is not limited toproviding a grilled appearance, but may also be used to add adistinctively different coloured layer on the surface of a food product,such as typically provided by a marinade.

Thus, according to a third aspect of the invention, a pet food productis provided, that has an underlying base colour throughout the productand a contrasting exterior colour that simulates grill marks on naturalmeat that has been chopped into chunky, irregularly-shaped, individualpieces prior to serving, the pet food product comprising a mixture of

-   (1) first individual pieces having a single base colour on their    exterior surface-   (2) second individual pieces having a portion of their exterior    surface bearing the contrasting colour, a minor portion of the    second pieces having the contrasting colour on substantially all of    their exterior surface.

In an embodiment, the present invention provides for an emulsion productin the form of individual pieces that vary in size and have irregularexterior surface contours that closely resemble a piece of natural meatin appearance, texture, and consistency. After forming, the emulsionmass is fragmented and custom-coloured while still in situ in theconfined processing zone. This contributes to forming the individualpieces that vary in size and have irregular exterior surface contoursand colouration. The disruption of the emulsion mass in the confinedprocessing zone is achieved by the injection of steam and/or bymechanical means. For example, a combination injector/shredder assemblymay be positioned in the confined processing zone to disrupt theemulsion mass and to inject colours which adhere to some of the exteriorsurfaces of the product.

In an alternative embodiment, a separate injector assembly for theexterior colourants could be located upstream or downstream of aseparate fragmenter device or shredder assembly. The shredder assemblycomprises means for disrupting the continuity of the structure of theemulsion as it coagulates. In an embodiment, the shredder assemblycomprises a series of baffles in the holding tube. In an alternativeembodiment, the shredder assembly comprises a grid of elementsorientated generally transversally to the direction of flow within theconfined processing zone. The fragmenter device or shredder assembly maythus be a simple arrangement of blades, baffles wires and/or bars tofragment, disrupt and/or shred the product mass while passing through oraround this assembly. The injector assembly can be a simple pipe withholes or nozzles to inject colourants.

The meat emulsion chunks of this invention are suitable for use as apartial or complete replacement for more expensive natural meat chunksin animal foods, that retain their integrity and shape when subjected tocommercial canning and sterilization procedures such as those requiredin the production of canned high moisture food products. The emulsionproduct of the present invention may also be placed in any sterilizablepackage or container.

The appearance of the present pet food product is enhanced by theaddition of a colourant to the product while it passes through theconfined processing zone. This colouring gives portions of the irregularexterior surface, but typically not the entire exterior surface of anindividual piece, a darkened appearance which simulates application of amarinade or grilling of the product on an outdoor barbecue grill or anygrill with a hot grate that imparts dark sear marks to food. Forexample, if a piece of real chicken breast were cooked on a grill,portions of the exterior would be darker than the interior. Aftercooking, being placed on a plate and cut into smaller individual pieces,some of the cut pieces of this real chicken would have perhaps oneexterior surface that is relatively dark and the other interior surfaceswould be relatively light. Other cut pieces of this real grilled chickenmight not have any darkening on any surface. This irregular colouring ofa portion, but typically not the entire surface of an individual piece,more closely simulates grilled natural meat products than the prior art.In the present invention, some of the individual pieces of the emulsionproduct may not have any colouring on the exterior surface, others mayhave a portion, but not all of the exterior surface coloured and a fewpieces may have colouring on substantially all of the exterior surface.This random colour scheme that darkens some exterior surfaces of thefinished product closely simulates a piece of natural meat that has beengrilled, seared or otherwise darkened on a portion of the exterior andthen chopped before serving.

Pet foods produced according to this invention that use meats and dryproteinaceous materials typically form an emulsion product. Vegetarian(meat-free) products produced according to this invention may or may notform an emulsion depending on the amount of lipids in the product.References hereinafter to emulsion products should therefore beunderstood to refer to any of the above situations. The pet food of thepresent invention is produced by a process which includes comminuting amix of meat material, such as meat (including fish and poultry) and/ormeat by-products, and/or vegetable protein under conditions which forman emulsion, or a low fat vegetable protein blend. One or more dryproteinaceous materials may, if desired, be included in theemulsion/blend to increase the protein content, particularly if the meatmix contains a relatively large proportion of low binding or fillermeats. The emulsion is comminuted under conditions which concurrentlyincrease emulsion fineness and rapidly heat the emulsion to atemperature above the boiling point of water, and preferably betweenabout 104° C. to about 118° C., at which temperature coagulation anddenaturing of protein in the emulsion proceeds at a very rapid rate. Thehot emulsion is immediately pumped by centrifugal force from thecomminuting equipment directly into a confined processing zone, such asan elongated hold tube, while maintaining the emulsion mix at a pressureabove the vapor pressure of the mix. The emulsion is retained in theconfined processing zone (“CPZ”) under such pressure until the proteinhas coagulated to an extent to set the emulsion and form a firm emulsionproduct, that is, within 5 minutes and generally for between a fewseconds to about 3 minutes. The shredder assembly disrupts the emulsionproduct in the zone. Liquids that include colourants are injectedproximate the shredder assembly.

Pressure at the downstream end of the confined processing zone isreduced to a value below the vapor pressure of the emulsion, therebygenerating steam in situ in the emulsion. The presence of steamgenerated in the confined emulsion mass by the vaporization of waterserves to further disrupt the emulsion mass into irregular individualchunks or pieces which are discharged from the tubular processing zone.Further sizing and chopping can occur to selected individual piecesdownstream of the hold tube, depending on the intended use of theproduct.

The pet food of the present invention has an appearance, texture andstructure which closely simulates natural grilled or roasted meatchunks. The food product produced by this process may be used as apartial or complete replacement for natural meat chunks in a variety ofanimal foods. These animal food products may be prepared by canning andretorting operations and/or they may be placed in any sterilizablepackage or container.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a food production process according to thepresent invention;

FIG. 2 is an enlarged photograph of a prior art pet food. The pet foodin FIG. 2 has been produced using some of the teachings of the '939patent and has been marketed under the brand Mighty Dog® pet food byNestle Purina PetCare Company of St. Louis, Mo.

FIG. 3 is an enlarged photograph of a prior art pet food. The pet foodin FIG. 3 has been produced using some of the teachings of the '939patent and has been marketed under the brand Friskies® pet food NestléPurina PetCare Company of St. Louis, Mo.

FIG. 4 is an enlarged photograph of a pet food of Example 1 of thepresent invention. The product is intended to simulate a piece of meatthat has been grilled and then chopped. In other words, the product hassimulated grill marks, which are dark surfaces on the exterior of somechunks.

FIG. 5 is an enlarged photograph of a pet food of Example 2 of thepresent invention. The product is intended to simulate a piece ofnatural fish that has been grilled and then chopped. In other words, theproduct has simulated grill marks, which are dark surfaces on theexterior of some chunks.

FIG. 6 is an enlarged photograph of a prior art pet food. The pet foodin FIG. 6 has been marketed under the brand Pedigree®, LittleChampions®, Grilled Cuts in Sauce™ with chicken by Kal Kan Foods, Inc.of Vernon, California. Real grill marks have been seared onto some ofthe exterior surfaces of this product.

DETAILED DESCRIPTION

Referring to the drawing in greater detail, FIG. 1 illustrates a foodproduction process and apparatus 18 including an injector/shredderassembly 20 constructed in accordance with a preferred embodiment of thepresent invention. The food production apparatus 18 is operable toproduce a food product for pets. The injector/shredder assembly 20 islocated in a hold tube 26 of the food production apparatus 18 and isoperable to disrupt the food product inside the hold tube 26 to obtainan improved food product and to inject liquid colourants. The foodproduction process can begin with meats and/or vegetable proteinsources. The process will first be explained using meats.

In preparing pet food chunks in accordance with the method of thepresent invention, a mixture of vegetable protein sources and/or naturalmeat materials, including both meat from mammals, fish or fowl and/ormeat by-products, having the requisite quality, ingredient cost andpalatability, is formulated, ground and, in the case of there beingsufficient fat present, as with meat protein containing fat, emulsified.The vegetable protein sources and/or meat and/or meat by-products usedmay be selected from a wide range of components, with the type andamount of meat material used in the formulation depending on a number ofconsideration such as the intended use of the product, the desiredflavor of the product, palatability, cost, availability of ingredients,and the like. Vegetable protein sources could be from, but not limitedto, soy, corn, rice, oil seed meals (for example, peanut, sunflower,linseed or canola) and wheat. Both meat (i.e. skeletal tissue andnon-skeletal muscle) from a variety of mammals, fowl and fish, and/ormeat by-products (i.e. the non-rendered clean parts, other than meat,derived from slaughtered mammals, fowl or fish) may be used as the meatmaterial. Thus, the term meat material as used herein is understood torefer to dehydrated and non-dehydrated meat and/or meat by-products,including frozen materials. The meat mix may contain whole carcass meat,carcass portions or meat by-products approved for use in animal foods,such as mechanically deboned beef, chicken or fish, beef and pork liver,lungs, kidney, and the like. Typically the meat material is formulatedto contain a maximum of about 25%, and preferably below about 15%, byweight of fat.

Additives which are used in conventional meat emulsion products may bemixed with the meat material and included in making a base meatemulsion, such as salt, spices, seasoning, sugar, and the like inamounts sufficient to provide the product with desired tastecharacteristics. In addition, minor amounts of other dry ingredientssuch as, for example, vitamins, minerals, flavors, and the like, mayalso be added to the meat emulsion. One or more dry proteinaceousmaterials, such as, for example, wheat gluten, soy flour, soy proteinconcentrate, soy protein isolate, egg albumin and nonfat dry milk, mayalso be included in the base meat emulsion to improve emulsion stabilityand binding, impart flavor, and reduce formulation costs. The inclusionof the dry proteinaceous materials in the emulsion is particularlyadvantageous in the production of product intended for use as a petfood, for it enables the processor to use meat materials having aprotein to fat ratio and myosin to total protein ratio which wouldotherwise be of marginal acceptability for use in preparing meatemulsion products. If a dry proteinaceous material is included, the meatcomponent may range from about 60% to about 95% by weight and all of thedry proteinaceous components may range from about 40% to about 5% byweight of the total emulsion. Generally, as the fat content and moisturecontent of the meat material used are increased, the level of dryproteinaceous material in the emulsion is increased accordingly. Theemulsion may be given a desired base colour by the inclusion of asuitable reliable base colourant material such as iron oxide—red oryellow.

While the formulation of the emulsion may vary widely, the emulsion,including the dry proteinaceous material, should have a protein to fatratio sufficient to form a firm emulsion product upon coagulation of theprotein with no sign of emulsion instability, and the protein content ofthe emulsion must be such as will enable the emulsion, upon being heatedto a temperature above the boiling point of water, to coagulate and forma firm emulsion product within a short period of time, that is, withinabout 5 minutes, and, preferably within 3 minutes, after being heated tosuch a temperature. Thus, the meat materials and the additives,including the dry proteinaceous material (if used) are mixed together inproportions such that the meat material is present in an amount ofbetween about 55% to 95% by weight, and preferably from about 65% to 85%by weight of the meat emulsion, with the meat emulsion having a proteinto fat ratio of at least about 1.5:1, with a protein to fat ratio ofbetween about 2:1 to 7:1 being preferred. While a higher protein to fatratio may be used in the meat emulsion, it is generally not preferredsince it would increase ingredient costs without providing anysignificant benefits. It is generally preferred to use a blend of meatand meat by-products as the meat material in the meat emulsion. However,the meat emulsion may be formulated using only meat by-products as themeat material, provided that the resulting meat emulsion, including thedry proteinaceous material (if used), has a protein to fat ratio of atleast about 1.5:1.

In addition, the meat emulsion should be formulated to contain betweenabout 45% to 80% by weight moisture, with the moisture contentpreferably being controlled between about 50% to 75% by weight of themeat emulsion, i.e. the meat materials and additives. The exactconcentration of water in the emulsion will, of course, depend on theamount of protein and fat in the emulsion.

The meat mix selected for use is passed through a grinder to reduce themeat material into pieces of substantially uniform size. Generally it ispreferred to pass the meat through a grinder equipped with a 1 cm orsmaller grinding plate. While satisfactory results may be obtained bygrinding the meat to a particle size larger than 1 cm, the use of suchlarger meat particles is generally not preferred. If the meat materialsto be used are in a frozen condition, they must first be prebroken orcut into pieces in order to reduce the size of the pieces going into thegrinder. While the size of the pieces will depend on the size of themeat grinder intake, normally the frozen meat material is cut intopieces about 10 cm square.

After grinding, the mix of meat particles is conveyed to a holding tankin which the meat mix preferably is heated to a temperature of betweenabout −1° C. to 7° C., such as by hot water jacketing, steam injection,and the like to facilitate pumping of the meat mix.

The mix of ground meat particles is then comminuted under conditions,which emulsify the meat material and form a base meat emulsion in whichthe protein and water of the meat mixture form a matrix thatencapsulates fat globules. The meat material may be emulsified by anyconventional procedure and equipment commonly used in meatemulsification such as by using a mixer, blender, grinder, silent cutterchopper, emulsion mill, and the like which is capable of breaking up anddispersing the fat as globules in the protein slurry to form anemulsion. Typically the temperature of the meat emulsion increasesduring the emulsification process. This heating of the meat emulsion isnot objectionable as long as the temperature does not increase to thepoint that protein denaturation begins to occur at an undesirable rateat this stage of the process. The temperature of the meat mixture duringemulsification should be maintained below about 49° C. in order tominimize protein denaturing at this stage of the process. According to apreferred embodiment of the invention, the meat material is passedthrough an emulsion mill to emulsify the meat material with the emulsionbeing heated to a temperature between about 10° C. to 49° C., preferablybetween about 35° C. to 46° C.

The additives to be incorporated in the meat emulsion, including dryproteinaceous material (if used), may be added to the meat mix prior toemulsification. Alternatively, it is frequently preferable toincorporate the additives, particularly the dry proteinaceous material,in the meat mix after emulsification of the meat. Since the addition ofthe dry proteinaceous material increases the viscosity of the emulsion,better emulsification is obtained when the meat mix is emulsified beforethe addition of the dry proteinaceous material, which results in theformation of a viscous meat emulsion.

The viscous meat emulsion thus obtained by inclusion of the dryproteinaceous material in the emulsion preferably is then deaerated byany conventional procedure such as by processing it through a vacuumstuffer, to remove occluded air which could disrupt the product matrixand reduce its binding capacity.

The meat emulsion is again comminuted to increase the fineness of theemulsion and is rapidly heated to a temperature above the boiling pointof water, at which temperature the coagulation of protein in theemulsion proceeds so rapidly that the emulsion is set and a firmemulsion product formed within a very short period of time. It has beenfound that rapidly heating the viscous meat emulsion to a temperatureabove the boiling point of water, and generally between 104° C. and 118°C., will result in the protein in the emulsion coagulating to set theemulsion and form a firm emulsion product within about 5 minutes andtypically from a few seconds to about 3 minutes after heating. Inaddition, heating the meat emulsion, which has a moisture content ofabout 45% to 80% by weight, to such temperature results in vaporizationof the emulsion water to form steam in the body of the emulsion masswhen it is at or near atmospheric pressure. Preferably the emulsion isprocessed in equipment in which the emulsion is heated to such elevatedtemperatures while it is being comminuted such as by mechanical heating.According to a preferred embodiment, the viscous meat emulsion, which isat a temperature of between about 30° C. to 40° C. is pumped through anemulsion mill in which the meat emulsion is subjected to shearing toincrease the fineness of the emulsion and almost simultaneously heat theemulsion to between about 104° C. to about 118° C. through rapidmechanical heating. Thus, the emulsion preferably is heated to suchelevated temperatures in a period of less than about 60 seconds.

Control of the emulsion temperature within the desired range can beeffected adjusting such factors as the feed rate into the emulsion mill,the rotational speed of the emulsion mill, and the like, and can readilybe determined by those skilled in the art.

The hot meat emulsion, which is at a temperature above the boiling pointof water and preferably in the range of between about 104° C. to 118°C., is pumped under positive pressure through the equipment in which itis comminuted and heated into a confined processing zone, whichpreferably is in the form of an elongated tube, and is retained in theconfined processing zone at a pressure above the vapor pressure of theemulsion until a firm product forms by coagulation. To obtain formationof individual pieces with irregular exterior surface contours, aninjector/shredder assembly is placed in the hold tube to promotedisruption and cutting of the emulsion. In an alternative arrangement,the shredder assembly may be separate from the injector assembly. Theshredder assembly comprises disruption means to disrupt the continuityof the structure of the coagulated emulsion. The disruption means maycomprise an object placed in the flow stream and around which theemulsion is forced to divide in order to continue moving toward thedischarge end of the hold tube. Thus it may be a grid of cuttingelements generally disposed transversally to the direction of materialflow in the hold tube. Alternatively, or in addition, it may comprise aseries of baffles. In another alternative embodiment, the disruption maybe accomplished with the injection of steam into the hold tube.

Because of the injector/shredder assembly the product is disrupted inthe confined processing zone to enhance formation of individual pieceswith irregular exterior surface contours and colour is added. At theelevated temperature in the tube, protein coagulation proceeds at a veryrapid rate while the desired colour is imparted to some exteriorsurfaces of the product. The period of time required for the hotemulsion to set sufficiently to form a firm product will depend on anumber of factors, such as the temperature to which the emulsion isheated and the amount and type of protein in the emulsion. A residencetime of between a few seconds to about 3 minutes, and usually betweenabout 1 to 1.5 minutes, in the elongated tube is generally sufficientfor the protein to coagulate sufficiently. The residence time in theelongated tube can be controlled by adjusting the flow rate of theemulsion to the elongated tube and/or by adjusting the length of theelongated tube. The dimensions of the holding tube are not critical butmust be sufficient to provide the emulsion with sufficient retentiontime in the tube for the emulsion to set. In practice, tubes having alength of between about 3 m and about 25 m and an internal diameter ofbetween about 4 cm and about 60 cm provide sufficient retention time toform the emulsion product. Tubes of various cross-sectional shapes maybe used, such as circular, square, octagonal, and the like.

An injector/shredder assembly is positioned to inject liquids containingcolourant(s) into the emulsion while in the hold tube. Colourants areingredients, which naturally impart colour to a food product.Colourants, useful with the present invention include, but are notlimited to, caramel colour. Other brownish shades ranging to black maybe utilized. Water-soluble or oil-soluble colourants may be suitable foruse in this invention. The colourant is mixed in an aqueous solutionprior to contact with the food product. The aqueous solution is fromabout 30% to about 60% colourant by weight and from about 70% to about40% water by weight. Other flavors and/or nutritional ingredients mayalso be added to this aqueous solution. In order to affix the colourantto the food product passing through the elongated hold tube, the aqueouscolourant solution should have an opposite electrical charge to the foodproduct. Because products containing meat have a naturally occurringpositive charge, it is useful to use colourant with a negative charge,but it is sufficient that the charges be opposite. It is within thescope of this invention to have a negatively charged product mass and apositively charged colourant.

In the case of caramel colours, these fall into four general Classes,depending on the method of production. Caramel colour Class 1 isslightly negative, Class 3 caramel colour is positively charged whereasClass 2 and 4 are negatively charged. If the food product has a overallpositive charge, Class 2 and 4 and, to a lesser extent, Class 1 caramelcolour are suitable, whereas positively charged caramel colours will beuseful if the food product has an overall negative charge.

Caramel colour BC 145 (commercially available from Sethness Products Co.of Chicago, Ill.) is a Class 4 colour that is negatively charged and issuitable for use in this invention. Caramel Colour 111 (commerciallyavailable from DD Williamson, Louisville, Ky.) is also a Class 4 caramelcolour that is negatively charged and is suitable for use in thisinvention. Numerous other charged caramel colours are commerciallyavailable and may be suitable for use in this invention. Applicantsbelieve that it is unknown to fix colour on a food product usingopposing charges without the presence of a binder. In contrast, it iscommon in the food industry to use a protein source, such as a colouredbatter, to surround and impart colourants to a product. The colourantused in this invention should not be applied to the individual pieces ofproduct after they have exited the hold tube.

The effect of the combination of pumping the hot emulsion into thetubular processing zone by centrifugal force, subjecting the hotconfined emulsion to disruption from the injector/shredder assembly 20while the protein is coagulating at a rapid rate and injecting colour,together with the pressure exerted on the emulsion by pumping it througha confined zone and the internal generation of steam in the hot confinedemulsion, serves to disrupt the meat emulsion mass and facilitateformation of individual pieces with irregular surface contours which, byvirtue of the steam pressure, are rapidly discharged, already coloured,from the tubular processing zone into atmospheric conditions.

The set pieces discharged from the confined processing zone are in theform of discrete pieces or chunks having a temperature of about 98°C.-100° C., and a moisture content of about 50% to 65%, with the piecesvarying in size, shape and colouration. Upon discharge from theprocessing zone, the pieces are rapidly cooled by evaporative cooling toa temperature in the range of 83° C.-93° C. If desired, suitable cuttingmeans, such as a rotary cut-off knife, a water jet knife, a knife grid,or the like may be mounted at the discharge end of the elongated tube tocut the chunks into pieces of a desired size, e.g. from about 0.2 cm to5 cm or more. The meat emulsion chunks thus formed have excellentintegrity and strength and will retain their shape when subjected tocommercial canning and retorting procedures such as those required inthe production of canned foods having a high moisture content.

The meat emulsion pieces discharged from the confined processing zonemay be conveyed to a dryer to remove a large portion of the moisturetherefrom, and the dried product collected and stored. Alternatively,the meat emulsion pieces may be conveyed from the elongated tubedirectly to a canning operation in which layered chunks are filled intocans or pouches together with other ingredients, such as sauce, gravy,and the like, and the cans retorted. For example, in the production of acanned pet food product, a suitable gravy may be prepared by heating amixture of water, starch (or gums) and condiments. The meat emulsionchunks and gravy are filled into sterilizable packages or containers inthe desired proportions, the packages or containers are vacuum sealedand are then retorted under time-temperature conditions sufficient toeffect commercial sterilization. Convention retorting procedures may beused. Typically, a retorting temperature of about 118° C.-121° C. forapproximately 45-90 minutes is satisfactory in producing a commerciallysterile product.

Referring to FIG. 1, the food production process 18 begins with meatpreparation utilizing a grinder 28. Various kinds of frozen meat areground into small pieces and mixed in a first mixer 30 in desired ratiosas set forth in the examples given below. Other dry ingredients such asvitamins, and minerals are also added at this mixing step if desired.The first mixing process can be continuous or by batch. The mixed foodproduct is then passed to a first emulsifier mill 32, which is operableto heat and emulsify the food product. The emulsified food product isthen passed to a second mixer 34, and the food product is mixed withmajor dry proteinaceous material in amounts set forth in the examplesgiven below. The second mixer 34 preferably operates on a continuousbasis but can operate with batches of food product. The food product isthen passed, preferably by a pump 36, to an inlet pipe 38 for a secondemulsifier mill 40. In the inlet pipe 38, the food product isapproximately 40° C. at a pressure in the range of approximately 2.1kg/cm² to approximately 4.2 kg/cm². The food product is emulsified bythe second emulsifier mill 40, which is preferably a Siefer Mill, andthe food product is passed to the hold tube 26 at a pressure in therange of approximately 4.2 kg/cm² to approximately 8.4 kg/cm² and atemperature in the range of approximately 104° C. to approximately 118°C. and preferably 110° C. Under the desired temperature and pressureconditions in the hold tube 26, the food product starts to rapidlycoagulate.

As the food product passes through the hold tube it passes through theinjector/shredder assembly 20. The total length of the hold tube couldbe between about 3 m to about 25 m, and the length of the hold tubeleading up to the injector/shredder assembly 20 is between approximately10-70% of the length of the hold tube. The preferred length of the holdtube leading up to the injector/shredder assembly 20 is approximatelybetween 15 and 20% of the length of the hold tube. The injector/shredderassembly then disrupts and cuts the food product and injects liquidcolourants. A liquid, including colourants contacts and adheres to thefood product, which darkens a portion of the product simulating theappearance of being grilled. The colour solution is affixed to the foodproduct by forces of electrical attraction. The food product and thecolour solution have opposite charges. Thus, the colour solution bondsto the food product without additional binders. The liquid 17 isprovided by a metering pump 42, which transmits the liquid to theinjector/shredder assembly 20. The pump 42 should have an outputpressure that is higher than the pressure in the hold tube 26 and a flowrate of from about 1% to about 20% by weight of the product flow andpreferably about 3%. So for example, if 100 kg of product is passingthrough the hold tube per minute, the liquid 17 should be injectedthrough the injector/shredder assembly at between about 1 kg per minuteto about 20 kg per minute.

The pump 42 could be a positive displacement pump or any other type ofpump that provides sufficient output pressure to exceed the pressure inthe hold tube 26, avoid plugging and provide a sufficient flow rate ofcolourants from a reservoir, not shown, to the injector/shredderassembly 20. In an alternative embodiment, an injector assembly, notshown, may be separate from a fragmenter/shredder assembly, not shown.In this alternative embodiment, not shown, the pump 42 delivers thecolourant solution to the separate injector assembly which injectscolourants into the product mass as it passes through the hold tube 20.In this alternative embodiment, not shown, the injector assembly may beupstream or downstream of the separate fragmenter/shredder assembly. Thefragmenter/shredder assembly disrupts, fragments, and shreds the productmass as it passes through and/or around this assembly in the hold tube.

When the food product exits the hold tube 26, it is further cut intoindividual pieces by an end of tube cutting apparatus 44 after beingexposed to atmospheric pressure. Exposure to atmospheric pressure at thedesired boiling temperatures causes the food product to flash.Specifically, the food product rapidly expands. In combination, thedisruption and cutting of the emulsion by the injector/shredder assembly20, the flashing to atmospheric pressure at the discharge end of thehold tube 26 and final cutting into individual pieces gives a randomirregular surface contour to many of the individual pieces. Due to thecolour solution, which has been added to the product, a few of theindividual pieces will have colour on the entire exterior surface, otherindividual pieces will have no colour on the exterior surface, but manyof the individual pieces will have one or more exterior surfaces, butnot the entire exterior surface, darkened by the colour giving a grilledappearance to such pieces. In the preferred embodiment of the finishedproduct with colour, from about 10% to about 80%, and preferably fromabout 40% to about 50% of the individual pieces will have one or moreexterior surfaces, but not the entire exterior surface, darkened by thecolour giving the finished product the appearance of fresh meat that hasbeen grilled and cut into smaller pieces.

The cutting apparatus 44 may typically be a rotary cutter. Pieces in thedesired size range pass to a tumbler where they may be mixed with gravyfrom a gravy supply. After the meat and gravy are mixed, the combinationis passed to the filler, which packages the product in cans, pouches orother containers. Packaging the pieces in a transparent container,without gravy being added, enables the grilled or pan-fried appearanceof the product pieces to be advantageously exhibited.

FIG. 2 is an enlarged photograph of a prior art pet food. The pet foodin FIG. 2 has been produced using some of the teachings of the '939patent and has been marketed under the brand Mighty Dog® pet food byNestlé Purina PetCare Company of St. Louis, Mo. The colour of the petfood is generally uniform throughout the individual chunks. The shape ofthe individual chunks is also generally uniform with few irregularexterior surfaces.

FIG. 3 is an enlarged photograph of a prior art pet food. The pet foodin FIG. 3 has been produced using some of the teachings of the '939patent and has been marketed under the brand name Friskies® pet food byNestle Purina PetCare Company of St. Louis, Mo. The base colour of thepet food in this photograph is generally uniform throughout theindividual chunks. The shape of the individual chunks is also generallyuniform with few irregular exterior surfaces.

FIG. 4 is an enlarged photograph of the pet food of Example 1 of thepresent invention. The product is intended to simulate a piece of meatthat has been grilled and then chopped. The base colour of the pet foodin this photograph is generally uniform throughout the individualchunks, except there are dark exterior surfaces on some of the chunks,which simulates grill marks.

FIG. 5 is an enlarged photograph of a pet food of Example 2 of thepresent invention. The product is intended to simulate a piece ofnatural fish that has been grilled and then chopped. The base colour ofthe pet food in this photograph is generally uniform throughout theindividual chunks, except there are dark exterior surfaces on some ofthe chunks, which simulates grill marks.

FIG. 6 is an enlarged photograph of a prior art pet food. The pet foodin FIG. 6 has been marketed under the brand Pedigree®, LittleChampions®, Grilled Cuts in Sauce™ with Chicken by Kal Kan Foods, Inc.of Vernon, California. The base colour of the pet food is generallyuniform throughout the individual chunks; however real grill marks ordark lines have been seared onto one of the flat exterior surfaces ofsome chunks to enhance the appearance of the product. Many of theindividual chunks are generally rectangular in shape. On the surfacewith the dark lines, the base colour fills all of the surface, exceptwhere the dark line covers the base colour.

The following examples illustrate the invention. In the examples andelsewhere herein, parts and percentages are expressed by weight, unlessotherwise indicated.

EXAMPLE 1

A canned pet food product comprising chunks of emulsion in aqueous gravywas prepared by the following procedure. This product was intended tosimulate cut up pieces of beef that were grilled or marinated.Colourant(s) were added through the injector/shredder assembly to theexterior surface of the individual pieces to simulate a piece of meatthat was grilled and then chopped. In other words, the product hadsimulated grill marks, which were dark surfaces on the exterior of somechunks. A brown, reddish base colour gave a generally uniform colourthroughout the product, except where the simulated grill marks werelocated on an exterior surface. The simulated grill marks on theexterior surfaces were darker than the generally uniform base colour ofthe product. Red iron oxide was the base colour and was applied in anamount of about 0.2% by weight of the emulsion.

With references to FIG. 1, blocks of frozen meat were first cut orbroken into pieces about 10 cm in size and the pieces were ground in aconventional meat grinder 28 equipped with a 1 cm plate. The followingproportions of meat material were used in this product: Parts by MeatType weight Beef, mechanically separated 50% Lungs 35% Liver 15% Total:100%  Parts by Injection Solution weight Water 70% Caramel Colour 30%Total: 100% 

The ground meat was introduced into a mixer 30 in which it was heated bysteam injection to a temperature of about 0° C. After mixing, the blendof ground meat materials was fed into an emulsion mill 32 in which themeat was cut and sheared to form a meat emulsion which was heated bymechanical working during emulsification to a temperature of betweenabout 15.6° C. to 43° C. The warm meat emulsion was pumped from theemulsion mill into a mixer 34 where it was thoroughly mixed with a blendof dry ingredients containing the dry proteinaceous materials, togetherwith vitamins, minerals and spices to form a thickened, viscous meatemulsion containing about 74% meat material, 26% dry proteinaceousmaterial, and the balance vitamins, minerals and spices. The viscousmeat emulsion thus formed was pumped from the mixer into avacuum-stuffer to deaerate the emulsion.

After deaeration the viscous emulsion, which was at a temperature ofabout 30° C. to 40° C., was pumped into an emulsion mill 40 in which theemulsion was cut and sheared under conditions to increase the finenessof the emulsion and almost simultaneously heat the emulsion to atemperature of about 110° C. A firm meat emulsion product formed within2 minutes after heating. The hot emulsion was pumped directly from theemulsion mill into an elongated tube 26 having an internal diameter of6.35 cm and a length of 6.1 m. The hold tube 26, had a length todiameter ratio of about 30:1, and had an injector/shredder assembly 20positioned therein to fragment, disrupt and shred the product as itpassed through the assembly. This facilitated the formation ofindividual pieces with irregular surface contours. A liquid solution wasinjected by the injector/shredder assembly. The liquid solution wasabout 30% caramel colour and about 70% water by weight. The caramelcolour had a negative electrical charge and was BC 145 (commerciallyavailable from Sethness Products Co. of Chicago, Ill.). Theinjector/shredder assembly 20 was placed in the elongated hold tube 26to fragment, disrupt and shred the product and inject the aqueous coloursolution while the product moved through the tube. The colour solutionwas injected at a level of about 8% of the product flow. The flow rateof the emulsion through the tube was controlled to provide the emulsionwith a residence time of about 2 minutes in the tube.

An additional cutting system 44 in the form of a rotary cutter waspositioned at the discharge end of the elongated hold tube 26 to cut theproduct into individual pieces which had irregular exterior surfacecontours in the form of meat-like pieces or chunks varying in lengthfrom about 1.2 cm to about 5 cm or more. They had randomly locateddarkened—even blackened—patches, resembling grid marks from a hot grill.The individual chunks discharged from the tube were at a temperature ofabout 99° C. and had a moisture content of about 56%. The resulting meatemulsion pieces were filled into flexible pouches and were sealed andretorted under conditions sufficient to provide a commercially sterileproduct. After retorting, the pouches were allowed to cool to roomtemperature and stored for a month before being opened. The piecesretained their shape, integrity, and grilled meat-like appearance andtexture.

EXAMPLE 2

This example describes preparation of a fish-like product with exteriorcolour added through the injector/shredder assembly to simulate a pieceof fish that was grilled and then chopped. In other words, the producthad simulated grill marks, which are dark surfaces on the exterior ofsome chunks. The final product was prepared in aqueous gravy. Anorange/reddish base colour gave a generally uniform salmon-like colourthroughout the product except where the simulated marinated or grillmarks were located on an exterior surface. Red and yellow iron oxideswere the base colour and were applied in an amount of about 0.2% byweight of the emulsion. This base colour was added at the beginning ofthe mixing process to give a generally uniform colour throughout theproduct.

The procedure described in Example 1 was repeated, with the exceptionthat the following proportions of meat material were used: Meat TypeParts by Weight Fish 45% Liver 15% Lung 25% Chicken 15% Total: 100% 

Injection Solution Parts by Weight Caramel colour 15% Water 85% Total:100% 

EXAMPLE 3

This example describes preparation of a meat-free product with colourantadded through the injector/shredder assembly. The product is intended tosimulate chopped pieces of fish that are grilled or marinated. In otherwords, the product should have a generally uniform colour throughoutwith the presence of simulated grill marks on exterior surfaces. Basecolours are added to the initial formula to produce a generally uniformcolour through the product. In this example, an orange/reddish basecolour may be added to a simulated salmon product.

The resultant pieces are irregularly shaped with a layered internaltexture resembling the flaked structure of salmon. They have anorange/reddish-coloured hue and blackened patches over the exteriorsurfaces, except where surfaces have been divided by a rotary cutterexternal to the holding tube. Vegetable Protein Parts by weight WheatGluten 30% Vegetable oil  7% Water 63% Total: 100% 

Liquid Injection Solution Parts by weight Caramel Colour 35% Water 65%Total: 100% 

The ingredients are introduced into a mixer. The ingredients are heatedby steam injection to a temperature of about 27° C. The viscous,emulsion-like mixture thus formed is pumped from the mixer into avacuum-stuffer for deaeration.

After deaeration, the viscous mixture, which is at a temperature ofabout 32° C., is pumped into an emulsion mill in which the viscousmixture is processed to heat it very quickly to a temperature of about107° C. At such an emulsion temperature, protein coagulation proceedsvery rapidly, so that a firm product is formed within 2 minutes afterheating. The hot emulsion-like mixture is pumped directly from theemulsion mill into an elongated tube having an internal diameter of 6.35cm and a length of 6.1 m. An injector assembly is positioned about 30%of the distance along the tube and a fragmenter/shredder assembly ispositioned at about 60% along the elongated hold tube to disrupt,fragment and shred the product as it moves through the tube and injectliquids including colour. The liquid solution is about 35% colour andabout 65% water by weight. The flow rate through the tube is controlledto provide a residence time of about 2 minutes in the tube.

A firm product is continuously discharged from the elongated hold tube.A rotary cutting blade is positioned at the discharge end of theelongate hold tube to cut the product into individual pieces which haveirregular exterior surface contours in the form of meat-like pieces orchunks mostly varying in length from about 1.5 cm to about 6 cm or more.The individual chunks discharged from the tube are at a temperature ofabout 99° C. and have moisture content of about 55%. The resultingchunks or pieces are filled into sterilizable transport packages and aresealed and retorted under conditions sufficient to provide acommercially sterile product. After retorting, the pieces retain theirshape, integrity, and meat-like appearance and texture.

Although the present invention has been described with reference tospecific examples and preferred embodiments, it will be understood thatchanges, modifications and variations of composition and procedure maybe made within the principle and scope of the invention as set forth inthe appended claims.

1. A process for producing a pet food comprising: mixing a proteinsource to produce an emulsion; heating said emulsion above the boilingpoint of water; pressurizing said emulsion in a confined pressurizedzone; coloring said emulsion in said confined pressurized zone; anddischarging said emulsion in discrete pieces or chunks of pet food. 2.The process of claim 1 wherein said protein source comprises at leastone source selected from the group consisting of a vegetable source, ameat source, and a meat by-product source.
 3. The process of claim 2wherein said vegetable source comprises at least one source selectedfrom the group consisting of a soy source, a corn source, a rice source,a peanut source, a sunflower source, a linseed source, a canola source,and a wheat source.
 4. The process of claim 2 wherein said meat sourcecomprises at least one source selected from the group consisting of abeef source, a chicken source, a fish source, and a pork source.
 5. Theprocess of claim 4 wherein said meat source contains from about 15% toabout 25% fat by weight.
 6. The process of claim 4 wherein said meatsource contains less than 15% fat by weight.
 7. The process of claim 1wherein the emulsion has a protein to fat ratio of at least 1.5:1. 8.The process of claim 1 wherein said emulsion is heated to a temperaturebetween about 104° C. and about 118° C.
 9. The process of claim 1wherein said emulsion has a moisture content from about 45% to about 80%by weight.
 10. The process of claim 1 wherein said confined pressurizedzone is at least one of an elongated tubular member and a holding tube.11. The process of claim 10 wherein the emulsion is restricted in saidholding tube for a predefined period of time.
 12. The process of claim10 wherein the emulsion is contained in said holding tube having apressure above the vapor pressure of said emulsion.
 13. The process ofclaim 12 wherein the emulsion is retained in said holding tube under apressure greater than its vapor pressure until the protein in saidemulsion has coagulated to form a firm emulsion.
 14. The process ofclaim 1 further comprising the step of disrupting the emulsion to formindividual pieces of pet food having irregular exterior surfacecontours.
 15. The process of claim 14 comprising disrupting the emulsionmechanically.
 16. The process of claim 15 wherein said step ofdisrupting the emulsion comprises using an injector/shredder assembly.17. The process of claim 16 wherein said injector/shredder assemblycomprises at least a an injector assembly and a shredder assembly. 18.The process of claim 17 wherein said injector assembly comprises a meansof injecting steam to disrupt the emulsion.
 19. The process of claim 16comprising the step of utilizing said injector assembly to inject anegatively charged colorant into the emulsion.
 20. The process of claim1 wherein coloring the emulsion comprises adhering a colorant to saidemulsion.
 21. The process of claim 20 wherein said colorant comprises atleast one colorant selected from the group consisting of an oil basedcolorant and a water-soluble colorant.
 22. The process of claim 21wherein said colorant further comprises at least one component selectedfrom the group consisting of a flavor and a nutrient.
 23. The process ofclaim 20 wherein said colorant is negatively charged with respect to theemulsion.
 24. The process of claim 23 wherein said colorant comprises awater soluble, carmel color having a negative charge with respect to theemulsion.
 25. The process of claim 20 wherein said colorant is capableof adhering to the emulsion without the presence of a binder.
 26. Theprocess of claim 1 wherein said discharging comprises the step ofremoving said emulsion from said confined pressurized zone and cuttingsaid colored emulsion in pieces of varying size, shape and color. 27.The process of claim 26 wherein said colored emulsion has a moisturecontent from about 50% to about 65% by weight.
 28. A process forproducing a pet food having a layered, meat-like appearance and chunky,irregularly-shaped, individual pieces having a darkened exterior surfaceto simulate grill marks which comprises: passing a product mass througha confined processing zone; and contacting a portion of the product masswith a colorant while in the confined processing zone.
 29. The processof claim 28 wherein said product mass consists of an emulsion comprisingat least one source selected from the group consisting of a meat sourceand dry proteinaceous source.
 30. The process of claim 28 wherein saidproduct mass comprises less than 15% fat by weight.
 31. The process ofclaim 28 wherein said product mass has a moisture content from about 50%to about 65% by weight.
 32. The process of claim 28 wherein saidcolorant adheres to the emulsion without the presence of a binder. 33.The process of claim 28 wherein said colorant is selected from the groupconsisting of water-soluble colorants and oil soluble colorants.
 34. Theprocess of claim 28 wherein said colorant is negatively charged withrespect to said product mass to promote adhesion of said colorant tosaid product mass.
 35. The process of any claim 28 wherein said colorantcomprises a colored solution, which comprises from about 30% to about60% colorant by weight and from about 70% to about 40% water by weight.36. The process of claim 35 wherein said colored solution is injectedinto said confined processing zone at a pressure that is higher than thepressure inside said confined zone and at a flow rate from about 1% toabout 20% by weight of the product mass flow rate.
 37. The process ofclaim 28 wherein said confined processing zone comprises a holding tubeunder a pressure greater than its vapor pressure and the processcomprises maintaining the pressure until the protein in said emulsionhas coagulated to form a firm emulsion.
 38. The process of claim 37further comprising the step of disrupting the emulsion in the holdingtube to cause it to be divided into the said chunky, irregularly-shapedpieces.
 39. A pet food product comprising individual pieces of a foodproduct mass having a base color and a contrasting exterior color thatsimulated grill marks on natural meat that has been chopped intoirregularly shaped individual pieces prior to serving.
 40. The pet foodproduct of claim 39 wherein said pieces consist of a solidified emulsioncomprising at least one source selected from the group consisting of ameat source, a dry proteinaceous source and a vegetarian food source.41. The pet food product of claim 40 wherein the exterior colorcomprises a colorant selected from the group consisting of water-solublecolorants and oil-soluble colorants.
 42. The pet food product of claim41 wherein said colorant adheres to the emulsion without the presence ofa binder.
 43. The pet food product of claim 41 wherein said colorant isnegatively charged with respect to said product mass pieces to promoteadhesion of said colorant to said pieces.
 44. The pet food product ofclaim 39 wherein said pieces comprise less than 15% fat by weight. 45.The pet food product of claim 39 wherein said pieces have a moisturecontent from about 50% to about 65% by weight.
 46. The pet food productof claim 39 wherein a minor portion of the pieces has the contrastingcolor on substantially all of their exterior surface.
 47. The pet foodproduct of claim 46 comprising a mixture of said pieces with furtherindividual pieces having the single base color on substantially theirentire exterior surface.
 48. A pet food product that has an underlyingbase colour throughout the product and a contrasting exterior colourthat simulated grill marks on natural meat that has been chopped intochunky, irregularly-shaped, individual pieces prior to serving, the petfood product comprising a mixture of (1) first individual pieces havinga single base colour on their exterior surface (2) second individualpieces having a portion of their exterior surface bearing thecontrasting colour, a minor portion of the second pieces having thecontrasting colour on substantially all of their exterior surface. 49.The product of claim 48 wherein said second pieces comprise less than15% fat by weight.